The theme is "story of WHAT IF"!!
Lilith / Pixy has gathered "what if" stories of "Kangoku Senkan (Inescapable Battleship)" and "The Group Sex Club."
You can see another development or ending with this collection!

The Group Sex Club: Maki and Shiori Edition
"What if Maki and Shiori are attacked by the evil desire in the future where the hero is gone?"

The Group Sex Club: Tomomi Edition
"What if Tomomi, designated as a shrine maiden, could live through the gangbang?"

The Group Sex Club: Chiaki Edition
"Sister's ending. What if the brother tries to make up with the sister?"

The Group Sex Club: Aiko Edition
"What if Teacher Aiko, designated as a shrine maiden, visits the school to see a doctor?"

Kangoku Senkan
"What if Bohgan has finished the perverted brainwashing of Rieri and Naomi, completed the mission and was to marry Rieri?"

[From DLsite English]